I think if you want to go as Ranged character (whether it is bows, or shurikens, or darts), then these 15 points from the start are quite helpful. Morrowind isn't Oblivion nor Skyrim when lower skill only lower your damage and disable some perks, yet you still hit anyone anytime. 15 additional points are countless arrows that will actually hit the target instead of just disappear. And when you're low lvl with almost no gold, then you don't like wasting 4 arrows for every successful hit. Not to mention that you're also pretty squishy at the beginning and when you're at 4HP, already used all potions and enemy will soon lead another attack, these +15 points decides about your success or failure. So for players playing with bow Bosmer is easiest race to start the game.
Disease resistance isn't helpful, yet same thing applies to Altmers. And Bosmer don't suffer because of magic weakness. Agree on Beast Tongue being useless though, making it on pair with Altmers with no abillity at all.

I've never considered marksman to be a usable weapon skill. The weapons for it are too bad. Maybe if you're roleplaying as an archer it might make sense, but you'd really want to go with a race with a higher base strength in that case so you can carry more loot and arrows, like Dunmer, and Dunmer also have +5 marksman. And if you want to play as a rogue, Khajiit makes more sense, because they have better-distributed stealth skill bonuses.

Bosmer are actually bad though. They waste +15 on a dump weapon skill, marksman; the control creatures power is virtually useless; and disease resistance is actually useless, I have not ever even once been inconvenienced by a disease in Morrowind. The only reason to pick them is if you want 50/50 base Agility and Speed and don't care about starting with 30 Strength.

When I first started playing, any of the diseases that sap strength were more than just an inconvenience for me (brown rot from bonewalkers at low level comes to mind). However, it fades away with both higher level and more playing experience.

The wood elf bonus for marksman is something that helps at low level. If you choose to use ranged weapons this bonus is not a bad one (although I tended to use the bound longbow when I was playing using marksman skill so I didn't need the wood elf ability)

I'm not necessarily defending the character - just saying that I could see those skill bonuses helping.

but the beast tongue power is completely useless unless you feel the need to charm kwama and rats.

ST

"Hurry, hurry! Last boat to Solstheim! Until the next one. Hah-ha-hah."